Reflecting telescope system

ABSTRACT

A dynamic reflecting telescope system having a support and a hollow spherical housing rotatably mounted thereon. A telescope is fixedly mounted within the hollow spherical housing for rotational movement therewith. The telescope is thermally insulated from the interior of the hollow spherical housing thereby defining two distinct volumes, the volume within the telescope being maintained at essentially the same temperature as the surrounding atmosphere, whereby definition is improved by eliminating variations in the index of refraction within the telescope. Monitoring means adjusts the tangential and radial position of the individual primary mirror portions to compensate for atmospheric turbulence.

United States Patent 1191 Mackay Feb. 12, 1974 REFLECTING TELESCOPE SYSTEM [76 Inventor: Anthony Mackay, Costa Brava 17, Primary Exammer pl?avld E k lb J 48, Madrid 20 Spain Attorney, Agent, or zrm Sonnc a r.

[22] Filed: Sept. 21, 1971 57 ABSTRACT [21] Appl. No.: 182,350 A dynamic reflecting telescope system having a support and a hollow spherical housing rotatably mounted thereon. A telescope is fixedly mounted within the [52] US. Cl 350/83, 350/615522222 hollow Spherical housing for rotational movement Ilrt. Cl. b therewith. The telescope is thermally insulated from Fleld of Search 6 the interior of the hollow Spherical housing thereby 3 0/319 defining two distinct volumes, the volume within the telescope being maintained at essentially the same [56] References Clted temperature as the surrounding atmosphere, whereby UNITED STATES PATENTS definition is improved by eliminating variations in the 3,603,664 9/1971 James 350/83 index of refraction within the telescope. Monitoring 38 .731 5/1959 Waale v 350/69 X I means adjusts the tangential and radial position of the 2,981,572 4/1961 Kuhne 1 350/82 X individual primal-y mirror portions to compensate for 3,348,790 10/1967 Crowder et al.... 350/85 X atmospheric turbulence 3,502,387 3/1970 Hadley 350/83 X 3,503,664 3/1970 Hadley 350/82 X 3 Claims, l4 Drawing Figures PAIENIEBHarzmu I 3,791,713

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F I G2 INVENTOR. AA/r/m/W'JMA BY REFLECTING TELESCOPE SYSTEM The present invention relates to reflecting telescopes. More specifically, the present invention relates to a dynamic reflecting telescope system.

Generally, telescope design is moving toward the use of mirrors of greater diameter to increase the light gathering ability of the telescope; the only real restriction residing in the optical characteristics or seeing ability of the atmosphere. In accepting a greater crosssectional area of light from the object being observed, stringent demands are made on the atmosphere; substantially uniform values of the index of refraction are required. Therefore, large diameter mirrors may be advantageously used only on occasions of excellent seeing.

With large diameter mirrors, rigidity of the optics is obtained by a very massive isolated foundation. Such an optical system is referred to as static. With a static approach, conventional mounting systems of proven reliability are scaled up to accommodate mirrors of increased diameter.

In contrast to the static approach, a dynamic sys- .tem may be provided having a lighter, adjustable prilated from the interior of the hollowspherical housing defining two distinct volumes, so that the interior of the telescope is maintained at substantially the same temperature as the surrounding atmosphere, whereby definition is improved by eliminating locally induced variations in the index of refraction of the medium (air) with the telescope. The primary mirror includes a plurality of individual mirror portions. Monitoring means adjusts the primary mirror portions to compensate for atmospheric turbulence. The monitoring means includes primary control mirrors movably arranged in substantial planar alignment with each of the mirror portions, secondary control mirrors positioned in the telescope for receiving reflected light from the primary control mirrors, detection means for receiving reflected light from the secondary control mirrors, and control means for adjusting the tangential and radial rocking movement of the individual primary mirror portions in response to the detection means.

It is an object of the present invention to provide a dynamic reflecting telescope system capable of improved resolution with increased light gathering power.

It is a further object of the present invention to provide a telescope-dome construction to eliminate variations in the index of refraction caused by the inducement of convection currents in the vicinity of the primary focus. i

It is a further object of the present invention to compensate for atmospheric turbulence.

It is a further object of the present invention to provide improved tracking rate control system.

It is a further object of the present invention to provide a dynamic reflecting telescope having a coude room mounted on the telescope to reduce the number of mirrors required for operation in the coude mode.

It is still a further object of the present invention to provide a dynamic reflecting telescope system having thermally insulated optical and working environments.

It is still a further object of the present invention to provide a dynamic reflecting telescope system capable of being pneumatically supported.

Other objects, aspects and advantages of the present invention, in addition to the object previously discussed, will be more fully understood from the detailed description when considered-in conjunction with the drawings as follows:

FIG. 1 is a perspective view of the dynamic reflecting telescope system with the hour angle equal to 0;

FIG. 2 is a sectional view of FIG. 1 taken through the plane of the meridian at a latitude of 15 showing the telescope in the cassegrain mode;

FIG. 3 is a top plan view taken along line 3 3 of FIG. 2;

FIG. 4 is a bottom plan view taken along line 4 4 of FIG. 2;

FIG. 5 is a sectional view taken along line 5 5 of FIG. 3 showing the telescope in the coude mode and the polar axis guide mirror rotated 45 clockwise;

FIG. 6 is a partial sectional view taken along line 6 6 of FIG. 5 with parts removed and showing the telescope in the prime mode;

FIG. 7 is a plan view taken along line 7 7 of FIG.

FIG. 8 is a plan view showing the individual mirror portions of the primary mirror;

FIG. 9 is a sectional view taken along line 9 9 of FIG. 8;

FIG. 10 is a sectional view taken along line 10 10 of FIG. 2; I 7

FIG. 11 is a sectional view taken along line 11 ll of FIG. 2; I

FIG. 12 is a sectional view taken along line 12 12 of FIG. 11; and

FIGS. 13A and 13B are partial sectional views taken along line 13 13 of FIG. 10 (view A showing the flexible armature disengaged from the hollow spherical housing and view B showing the flexible armature engaging the hollow spherical housing).. Referring to FIG. 1, the dynamic reflecting telescope system 20 is generally shown including the support 22, hollow spherical housing 24, and telescope or optical tube 26. The telescope 26 is positioned within the hollow spherical housing 24 and fixedly mounted thereto for rotational movement with the housing 24; see also FIG. 2. The optical tube 26 has eight beams 27 connecting the extended end of the optical tube 26 to rigidly maintain the cantilevered arrangement of the optical tube 26 within the hollow spherical housing 24.

Thermal insulation 28 insulates the interior 30 of the telescope 26 from the interior 36 of the hollow spherical housing 24; the interior 36 of the telescope 26being maintained at substantially the same temperature as the surrounding medium or atmosphere 32. Further, thermal insulation 34 insulates the interior 36 of the hollow spherical housing 24 from the atmosphere 32 to provide a separate working environment.

With the telescope 26 positioned within the hollow spherical housing 24 and thermally insulated from the interior 36 of the housing 24, the interior 30 of the telescope 26 and interior 36 of the housing define two dis tinct volumes which are thermally insulated from each other. Thus, the optical tube 2 6 is maintained at essentially the same temperature as the atmosphere so that resolution or definition is improved by eliminating locally induced variations in the index of refraction present within the interior 30 of the telescope 26 caused by temperature variation. Further, maintaining the optical tube 26 at essentially the temperature of the atmosphere 32 eliminates the need for a prolonged cooling down period at the beginning of each observation night due to the daytime accumulation of heat in the structural numbers of the optical tube 26. A brief venting of the telescope 26 is all that is required.

Referring particularly to FIGS. 5, 8, and 9, monitoring means is included for adjusting the primary mirror 38 to compensate for atmospheric turbulence, providing constant control of small amplitude errors. The primary mirror 38 includes a plurality of individually mounted mirror portions or segments 40. Each primary mirror portion 40 also includes, as part of the monitoring means, a primary control mirror 41 movably arranged in substantial planar alignment therewith.

Pairs of secondary control mirrors 44 are mounted on the inner surface 46 of the conical superstructure or roof 48 of the telescope 26. Light detection means shown as photomultipliers 50 are positioned on the interior wall 51 of the telescope 26 for receiving reflected light. A light beam having the proper angle of reflection from a primary control mirror 44 will be reflected from the first to the second secondary control mirrors 44 of each pair and finally to the associated photomultiplier 50. A signal is transmitted from the photomultiplier through electronic circuit means (not shown) to actuate the control means 52, generally shown in FIG. 9.

Actuation of the control means 52 adjusts the tangential and radial position of the individual primary mirror portions 40. As seen in FIG. 9, each primary mirror portion 40 is hinged to a structural support number 54 for independent tangential and radial movement to compensate for errors up to plus or minus 10 seconds. (only the radial linkage of the control means 52 is shown in FIG. 9, the tangential linkage being similar is omitted for ease of description.) The radial control linkage 52 includes correcting rods 56, 57 and 58, tangential push rod 59, and flexible radial push rods 60 and 61 coupled to a linear cam 62 (spiral of Archimedes: P A B; where P equals cam follower displacement, 0 equals cam rotation, A equals cam follower minimum displacement and B equals the cam rotation factor) to produce a slight rocking motion in response to movement of the cam 62. An error of one second arc corresponds to a displacement of 0.3 mm. The primary mirror 40 is mounted on the structural support member 54 with a crossed-strip double hinge 64 to prevent backlash during tangential and radial adjustment.

Referring particularly to FIGS. 2, and 8, polar axis (PA) and declination axis (DA) tracking rate control means are provided to control the tracking rate. The first tracking system (PA) includes a guide mirror 66 and secondary control mirrors 68 and 70, respectively, mounted in diametrically opposed relationship on the inner surface 46 of the conical superstructure 48. A beam of light striking the first secondary control mirror 68 at the desired angle of reflection will reflect from the first to the second secondary control mirror 70 and then to the polar axis photomultiplier detector 72. The maximum error correction of the rotational movement of the hollow spherical housing 24 is slightly less than the rocking amplitude monitoring error correcting capability of the primary mirror portions 40, i.e., on the order of 3.3 mm. displacement, so that the first tracking rate control means can correct for large errors and the monitoring means will provide fine adjustments. FIG. 3 shows the east-west orientation of the PA guide mirror 66 and photomultiplier 72. A similar northsouth guide mirror system, including DA guide mirror 74 and photomultiplier 76 is provided for DA angle adjustments.

Referring particularly to FIGS. 2, 13A and 138, the desired tracking or sidereal rotation about the polar axis (PA) is provided with the aid of a linear motor 78 as described in the articles titled Linear Motor is Adapted to Drive Chart Recorder Pen," the Dec. 19, I966 issue of Product Engineering at page 59; and Linear Motor Operator Has Speed Control, the Nov. 22, 1967 issue of Product Engineering at page 62. The linear motor 78 is operated in conjunction with a flexible armature 80 and a slew motor 82. The flexible armature 80 and linear motor 78 engage the outer sur face of the spherical housing 24 to rotate the housing 24 about the-polar axis (PA) to track the observed object in response to signals from the photomultiplier 72.

Accurate determination of the polar axis (PA) is obtainfd by a lower declination drive 84 working in conjunction with a twin upper declination drive 86. The declination drives 84 and 86 engage the outer surface of the housing 24 at the opposite ends of the polar axis as shown in FIG. 2. The upper and lower declination drives 84 and 86 are powered by pillar-mounted torque motors (not shown). Further, the'declination drives 84 and 86 include brakemeans 88, see FIG. 11, to maintain the desired declination angle of thehollow spherical housing 24.

To set the DA, the PA drive including the linear motor 78 and flexible armature 80 are disengaged from the outer surface of the housing, and brake means 88 are disconnected and the torque motors activated to rotate the spherical housing 24 to the chosen declination angle. When the desired declination angle is obtained, brake means 88 are activated holding the desired declination angle orientation and allowing the housing 24 to rotate around the polar axis determined by a line through the declination drive tube pillar bearings 90 and 92, respectively, in response to engagement of the housing 24 by the PA drive. (The angle of the polar axis being 15 in FIG. 2.) Any corrections in the declination angle are obtained by slight rotation of the pillar tubes 94, see FIG. 11, in response to reflections from the DA guide mirror 74 which energizes the photomultiplier 76. The right ascension or polar axis drive engages the housing 24-and the slew motor 82 rotates the housing 24 to the correct value of the polar axis using the flexible armature 80 as a drive band. Reflected beams from the guide mirror 74 provide continuous correction of the declination coordinate; and guide mirror 66 and photomultiplier 72 activate the linear motor 78 to drive the housing 24 at a continuous sidereal rate of rotation.

A flexible cover 96 seals the outer wall openings required for the declination drive pillar tubes 94 and extends for the greater part of the perimeter of the hollow spherical housing 24.

Referring specifically to FIGS. 2, 5 and 6, the main topics include the primary mirror 38, the cassegrain secondary mirror 98, coude secondary mirror 100, and coude mirror 102. The optical tube 26 has three foci:

a prime focus (PF) 104 of f/l.3; a cassegrain focus (Cas F) 106 off/2.9 and a coude focus (CF) 108 of f/19. The primary mirror portions 40 are movably mounted on the structural support member 54 in the base 110 of the optical tube 26, see FIG. 5.

The conical superstructure 48 partially obstructs the aperture 112 of the optical tube 26and is supported by a strut assembly 114 connected to the upper sidewall 116 of the optical tube 26. An eight leaf shutter 117 controlled by individual hydraulic jacks (not shown) protects the telescope 26 from the atmosphere when not in use, by sealing into the conical superstructure 48, and retracts to expose the telescope 26 during observation, see FIGS. 1, 2 and 5. Additionally, a generally conical housing 118, axially aligned with the conical superstructure 48, is held in position by the strut assembly 114. The conical housing 118 closes the PF 104 and the secondary flip-flop means 120. The secondary flip-flop means 120 includes the central portion 122 of the cassegrain secondary mirror 98, the coude secondary mirror 100 and a suitable counterweight 124 for rotation of the-flip-flop means 120 about flip-flop axis 124, see FIG. 7. Magnetic latches 126 hold the flip-flop means 120 in position within the conical housing 118. To pivot the flip-flop means 120 it is rotated about axis 124.

The cassegrain secondary mirror 98 includes a central mirror portion 122 and removable outer circumferential portion 128. The outer circumferential portion is held by four hydraulic jacks-130 mounted to the floor 132 of the telescope 26. The hydraulic jacks 130 are positioned for vertical movement from the down position shown in FIGS. 5 and 6 in the coude and prime modes, respectively, to the up position shown in FIG. 2 for operation in the cassegrain mode for positioning the outer circumferential portion 128 about the central mirror portion 122, as shown in FIG. 2.

To obtain the prime mode, while the spherical housing 24 is in the stow position, the secondary flip-flop means 120, including the cassegrain sky baffle 131, is lowered from its normal up position within housing 118 to the down position shown in FIG. 6. The light shield 133 is retracted since baffling of reflected light is'not required. 7

For operation in the cassegrain mode, while the spherical housing 24 is in the stow position the coude mirror 102 is swung out of the path of the secondary light beam, the hydraulic jacks 130 move the outer circumferential portion 128 of the cassegrain secondary mirror into the up position, and the light shield 133 is partially extended to provide baffling of unwanted reflected light, see FIG. 2.

108 is obtained by utilizing elevators 136 which transport an observer from the floating bay 138 to the coude room 140. The coude room is mounted on the telescope 26 and thermally insulated from the interior 36 of the hollow spherical housing 24, so that the coude room 140 is maintained at substantially the same temperature as the interior 30 of the telescope 26. To gain access to the primary focus 104, the observer uses the ramp 141 which leads from the coude room 140 to the primary focus 104, see FIGS. 5 and 6. Entry is made in the stow position, although PF observation can be made at any elevation ofthe telescope 26.

The flowing bay 138 provides the working facilities and is supported on coasters 142 against the inner wall 144 of the spherical housing 24. A triangular bogey (not shown), similar to triangular bogey 145, maintains the axis of the bay guide 146 coincident with the PA. Thus,-the bay guide 146 maintains the proper orientation of the floating bay 138 for utilization of the elevators 136.

The hollow spherical housing 24 may be advantageously air supported. Since the housing 24 has a large surface area, air pressure on the order of a few atmospheres is sufficient to support the housing 24. Referring to FIG. 10, three coaster defining pads 148, 150 and 152, each positioned within a separate pressure supporting area, engage the outer wall 154 of the spherical housing 24 to provide equal gap spacing during slight displacement of the pillar bearings 90 and 92 and facilitate rotation of the housing 24. Flexible seals 155 border each separate pressure area to confine the air forming the air cushion support. Further, it is advantageous that the central support area 158 have a higher pressure than the surrounding areas which include the coaster pads 148, 150, and 152.

As perhaps best seen in FIGS. 1, 2 and 11, the hollow spherical housing 24 comprises an interwall lattice between the inner surface 144 and the outer surface 154 with space therebetween for thermal insulation 34, entrance ports, air conditioning, power cables, plumbing,

pillar tracks 156 and 158, and a balance system having wall insulation also surrounds the optical tube 26 and For operation in the coude mode, the outer circumferential portion 128 supporting the cassegrain sky baffle 131 is lowered to the down position thereby providvides access to the cassegrain focus 106 located at the 6 center of the hollow spherical housing 24 and at which point the polar axis, declination axis and optical axis (0A) intersect, see FIG. 2. Access to the coude focus coude room 140.)

It should be understood by those skilled in the art that various modifications may be made in the present invention without departing from the spirit and scope thereof, as described in-the description and defined in the appended claims. What is claimed is: 1. A dynamic reflecting telescope system having a support and a hollow spherical housing rotatably mounted thereon, wherein the improvement comprises:

a telescope fixedly mounted within said hollow spherical housing for rotational movement therewith;

first insulation means for thermally insulating the interior of said telescope from the interior of said hollow spherical housing, the interior within said telescope defining a first volume;

second insulation means for thermally insulating the interior of said hollow spherical housing from the atmosphere surrounding said hollow spherical housing, the interior within said hollow spherical housing defining a second volume;

a floating bay positioned within said hollow spherical ing areas, one of said supporting areas being centrally located and the remaining supporting areas surrounding said central support area, said central support area having a higher pressure than said rehousing to provide WO XltlHg facilities for observers; maining Surrounding Support areas; gu'de l 3 hqmomal onentanon a coaster pad within each of said remaining surroundof sa d floating bay within said rotatable hollow ing Support areas to engage said hollow Spherical Sphencal housmg; housing to equalize gap spacing during rotation of the first volume within said telescope being at essen- Said hollow Spherical housing and tially the same temperature as the atmosphere sur- 1 v flexible seals separating each of said supportlng arroundmg said hollow spherical housing to improve 8 definition by eliminating variations in the index of 3 fl I d refraction within said telescope and the second volynflmlc ectmg te escope System as recite ume within said hollow spherical housing being m clam 1 l f maintained at a different temperature to Suit the coasters positioned between said floating bay and the f t f the observers interior of said hollow spherical housing to support 2. A dynamic reflecting telescope system as recited Said floating y within Said hollow Spherical hous' i l i 1 i l di ing and allow relative movement between said pneumatic support means for providing s p rt to floating bay and said hollow spherical housing dursaid hollow spherical housing, said pneumatic suping rotation of said hollow spherical housing. port means defining a plurality of separate support- 

1. A dynamic reflecting telescope system having a support and a hollow spherical housing rotatably mounted thereon, wherein the improvement comprises: a telescope fixedly mounted within said hollow spherical housing for rotational movement therewith; first insulation means for thermally insulating the interior of said telescope from the interior of said hollow spherical housing, the interior within said telescope defining a first volume; second insulation means for thermally insulating the interior of said hollow spherical housing from the atmosphere surrounding said hollow spherical housing, the interior within said hollow spherical housing defining a second volume; a floating bay positioned within said hollow spherical housing to provide working facilities for observers; guide means for maintaining a horizontal orientation of said floating bay within said rotatable hollow spherical housing; the first volume within said telescope being at essentially the same temperature as the atmosphere surrounding said hollow spherical housing to improve definition by eliminating variations in the index of refraction within said telescope and the second volume within said hollow spherical housing being maintained at a different temperature to suit the comfort of the observers.
 2. A dynamic reflecting telescope system as recited in claim 1 including: pneumatic support means for providing support to said hollow spherical housing, said pneumatic support means defining a plurality of separate supporting areas, one of said supporting areas being centrally located and the remaining supporting areas surrounding said central support area, said central support area having a higher pressure than said remaining surrounding support areas; a coaster pad within each of said remaining surrounding support areas to engage said hollow spherical housing to equalize gap spacing during rotation of said hollow spherical housing; and flexible seals separating each of said supporting areas.
 3. A dynamic reflecting telescope system as recited in claim 1 including: coasters positioned between said floating bay and the interior of said hollow spherical housing to support said floating bay within said hollow spherical housing and allow relative movement between said floating bay and said hollow spherical housing during rotation of said hollow spherical housing. 